class_docstr: A representation of a node in the Tree
  Contains two main types of information:
      - Data relevant for the node
      - Links to children nodes
code: def __init__(
      self,
      split: Split,
      depth: int,
      left_child: "TreeNode" = None,
      right_child: "TreeNode" = None,
  ):
      self.depth = depth
      self._split = split
      self._left_child = left_child
      self._right_child = right_child
  
imports: from typing import Union, Tuple
  from .data import Data
  from .split import Split, SplitCondition
label_desc: Use image node_id 1 to create a new TreeNode object from inherited base classes: object with example: obj = TreeNode(split, depth, left_child, right_child)